Move hwui private headers to frameworks/base/libs/hwui/private

hwui already exports most of its headers, move its private headers
into its source directory.

Bug: 33630870
Test: m -j native
Change-Id: I4968d5aaaa68d9e92c826841d20f29cef349c9d8
diff --git a/include/private/README b/libs/hwui/private/README
similarity index 100%
rename from include/private/README
rename to libs/hwui/private/README
diff --git a/include/private/hwui/DrawGlInfo.h b/libs/hwui/private/hwui/DrawGlInfo.h
similarity index 100%
rename from include/private/hwui/DrawGlInfo.h
rename to libs/hwui/private/hwui/DrawGlInfo.h